WO1999066575A1

WO1999066575A1 - Method for producing solid polymer electrolyte-catalyst composite electrode and fuel cell

Info

Publication number: WO1999066575A1
Application number: PCT/JP1999/003226
Authority: WO
Inventors: Shuji Hitomi
Original assignee: Japan Storage Battery Co., Ltd.
Priority date: 1998-06-18
Filing date: 1999-06-17
Publication date: 1999-12-23

Abstract

A method for producing a solid polymer electrolyte-catalyst composite electrode used for a solid polymer electrolyte fuel cell, containing a solid polymer electrolyte and catalyst particles, and having a porous structure in which the catalyst particles are three-dimensionally distributed and pores are formed, whereby the catalyst material is supported in the solid polymer electrolyte-catalyst electrode safely in as high an active state as possible by means of a simple facility. A mixture of a catalyst material compound which is a compound of a metal in the platinum group capable of producing a catalyst material when reduced and a solid polymer electrolyte is prepared, and then the catalyst material compound in the mixture is chemically reduced using an inert gas containing hydrogen gas and hydrazine. An electrode produced using two catalyst material compounds, for example, a platinum compound and a ruthenium compound, or an iridium compound and a ruthenium compound is preferably used as an anode of a methanol-modification fuel cell or a direct-methanol fuel cell.

Description

Description Method for producing solid polymer electrolyte-catalyst composite electrode and fuel cell technical field>

The present invention relates to a method for producing a solid polymer electrolyte-catalyst composite electrode used for a fuel cell, a hydroelectric battery, and the like, and a fuel cell using the electrode produced by the method.

Solid polymer electrolyte fuel cells and solid polymer electrolyte water electrolyzers use, for example, an ion exchange membrane such as a perfluorosulfonate membrane as an electrolyte, and have an anode and a cathode on both sides of the ion exchange membrane. The electrodes are joined together, and a solid polymer electrolyte-catalyst composite electrode is used as these electrodes.

A solid polymer electrolyte-catalyst composite electrode refers to an electrode composed of a solid polymer electrolyte and a catalyst substance. Usually, the solid polymer electrolyte-catalyst composite electrode used above is composed of a solid polymer electrolyte and catalyst particles. A porous electrode having catalyst particles distributed three-dimensionally and having a plurality of pores formed therein.For example, a polymer having the same composition as the ion exchange membrane is converted into alcohol. A paste composed of a dissolved solid polymer electrolyte solution and catalyst particles is formed on a polymer film (generally a thickness of 3 to 30 μm), and then heated and dried. You. In addition, a PTFE (polytetrafluoroethylene) particle dispersion may be added to the paste as needed. In this electrode, the catalyst particles function as an electron conduction channel, the solid polymer electrolyte functions as a proton conduction channel, and the pores formed in the electrode function as supply and discharge channels for the active material and the product.

By the way, generally, the output voltage of a fuel cell is expressed as follows.

E _F = E r _K -7? _F -iR _F (1)

Ε _κ : Output voltage (V)

Er _F : Reversible potential (1.23V) V _F : Sum of oxygen reduction overvoltage and hydrogen oxidation overvoltage (V)

iR _F : Ohm loss due to cell structure etc.

In other words, it can be seen that in order to increase the output voltage of the fuel cell and improve the power generation efficiency, it is necessary to reduce the overvoltage by using a highly active catalyst substance.

On the other hand, the electrolysis voltage of hydroelectric power is expressed as follows.

E _w = E r _w + 77 _w + i R _w (2)

E _w: Electrolysis voltage (V)

Er _w : Theoretical decomposition voltage (1.23V)

77 _w : Total oxygen overvoltage and hydrogen overvoltage (V)

iR _w : Ohm loss due to cell structure, etc.

In other words, it can be seen that in order to lower the electrolysis voltage of the water electrolysis tank and improve the electrolysis efficiency, it is necessary to use a highly active catalyst substance to reduce the overvoltage as in the case of the fuel cell.

In other words, in a solid polymer electrolyte-catalyst composite electrode, in order to make the fuel cell and water electrolysis tank utilizing this as efficient as possible, the catalyst material supported on the electrode should be as high as possible suitable for each reaction. Must be active. However, the higher the activity of the catalyst particles, the more dangerous the manufacturing process of the solid polymer electrolyte-catalyst composite electrode. For example, in the method using a paste prepared by mixing the catalyst particles and the solid polymer electrolyte solution, when the catalyst particles are mixed with the solid polymer electrolyte solution, the solid polymer electrolyte is actuated by the action of the catalyst particles. The alcohol in the electrolyte solution reacts with the oxygen in the air to generate heat, which can cause ignition.

Therefore, in such a case, as a method for ensuring safety, for example, a method of preparing a paste in a nitrogen atmosphere, or a method in which the catalyst particles are wetted in advance with water so that the catalyst particles do not come into direct contact with air. A way was conceived. At present, a method is used in which a paste is prepared using catalyst particles pre-moistened with water, which can use a simpler manufacturing apparatus than the former method.

However, in this method, when the catalyst particles are wetted in advance with water, the catalyst particles come into contact with each other and agglomerate. As a result, even if highly active catalyst particles are used, the electrode is formed. There was a problem that the activity was low. <Disclosure of Invention>

The present invention relates to a method for producing a solid polymer electrolyte-catalyst composite electrode capable of supporting a catalyst substance in a solid polymer electrolyte-catalyst composite electrode with simple equipment, safely, and having as large an activity as possible. The purpose is to provide. In addition, the method of the present invention focuses on the fact that a catalytic substance such as a metal having a high catalytic activity also has a low catalytic activity in a compound thereof, and furthermore, a mixture of a solid polymer electrolyte and the above compound. It has been found that by reduction, the compound can be reduced to produce a catalytic substance. In this case, the solid polymer electrolyte is quickly adsorbed on the catalytic substance obtained by the reduction, and the protective effect is obtained. And the discovery that the catalytic substances generated by the reduction are prevented from coming into direct contact with each other to prevent aggregation of the generated catalytic substances. A mixture of a catalyst raw material compound and a solid polymer electrolyte is prepared, and the catalyst raw material compound in the mixture is chemically reduced.

That is, the method for producing a solid polymer electrolyte-catalyst composite electrode of the present invention is a method for producing a solid polymer electrolyte-catalyst composite electrode comprising a solid polymer electrolyte and a catalyst substance. A mixture of a catalyst raw material compound to be produced and a solid polymer electrolyte is prepared, and the catalyst raw material compound in the mixture is chemically reduced.

FIG. 1 is a diagram showing current-voltage characteristics of cells A and B, and FIG. 2 is a diagram showing current-voltage characteristics of cells C and D. FIG. 3 is a diagram showing current-voltage characteristics of cells E and F.

The solid polymer electrolyte-catalyst composite electrode to which the production method of the present invention is applied is an electrode composed of a solid polymer electrolyte and a catalyst substance, for example, a solid polymer electrolyte and a catalyst. A porous electrode in which the catalyst particles are three-dimensionally distributed in the solid polymer electrolyte and a plurality of pores are formed inside, and the electron conduction formed by the catalyst particles It has a channel, a proton conducting channel formed by a solid electrolyte, and a supply and discharge channel for an active material and products formed by a large number of pores. This electrode is used as a fuel cell or a water electrolyzer, for example, by being joined to both surfaces of an ion exchange membrane and further providing a power feeder thereon.

The catalyst raw material compound used in the production method of the present invention is a compound that can be a catalyst substance when the compound is reduced. If the catalyst substance functions as a catalyst, its shape, etc. Although the form of the catalyst substance is not particularly limited, for example, a substance that generates catalytic metal particles by reduction is used. The function as a catalyst is selected according to its use.For example, for fuel cells, those with high oxygen reduction capacity and hydrogen oxidation capacity, and for water electrolysis tanks, water oxidation capacity Those with high proton reduction ability are selected. In these cases, platinum group metals such as platinum, rhodium, ruthenium, iridium, palladium, and osmium are suitable as catalyst materials, and a solid polymer electrolyte-catalyst composite comprising these catalyst materials and a solid polymer electrolyte is manufactured. In this case, it is preferable to use a platinum group metal compound such as platinum, rhodium, ruthenium, iridium, palladium, or osmium as a catalyst raw material compound. Particularly, among these, the compound has a metal salt form. Preferably, for example, chlorides of platinum group metals are preferred.

When a metal compound is used, a mixture of several compounds may be used, or a complex or a double salt may be used. For example, by using a mixture of a platinum compound and a ruthenium compound, a platinum-ruthenium alloy can be formed by a reduction step. The mixture of the catalyst raw material compound and the solid polymer electrolyte may be in a liquid, solid or misaligned form as long as the catalyst raw material compound and the solid polymer electrolyte are mixed. It is preferable to use a porous body prepared by dispersing a catalyst raw material compound in a base made of a solid polymer electrolyte having a shape or the like, and to use such a porous body.

A mixture in which a catalyst raw material compound is dispersed in a matrix composed of a solid polymer electrolyte, A paste comprising a catalyst raw material compound, a solid polymer electrolyte solution, and, if necessary, a PTFE particle dispersion solution is formed on a polymer film (preferably 3 to 30 μm), and heated and dried.

Alternatively, a paste consisting of a catalyst raw material compound and a PTFE particle dispersion solution is formed into a film (preferably fliff 3 to 3θΛίπι) on a polymer film, heated and dried, and then a solid polymer electrolyte solution is applied and impregnated. , Let it dry,

Alternatively, a paste comprising a catalyst raw material compound, a solid polymer electrolyte solution, and, if necessary, a PTFE particle dispersion solution is applied onto a conductive porous carbon electrode substrate, and heated and dried.

Alternatively, a paste consisting of a catalyst raw material compound and a PTFE particle dispersion is applied to a conductive porous electrode substrate, heated and dried, and then a solid polymer electrolyte solution is applied, impregnated, and dried. It is preferable that it is produced by

If necessary, carbon particles may be added to the above-mentioned paste, in which case the carbon particles play a role in forming the above-mentioned electron conduction channel. Further, a mixture of the catalyst raw material compound and the solid polymer electrolyte may be bonded to both sides or one side of the ion exchange membrane.

The solid polymer electrolyte is preferably made of an ion exchange resin, and is preferably a sulfonic acid type polymer solid electrolyte of perfluorosulfonic acid or styrene-divinylbenzene.

In order to reduce the catalyst raw material compound in the prepared mixture of the catalyst raw material compound and the solid polymer electrolyte, from the viewpoint of safety described above, the catalyst raw material compound and the solid polymer electrolyte must be mixed before the reduction treatment. It is preferable to sufficiently evaporate the solvent of the solid polymer electrolyte such as alcohol in the mixture. Then, it is preferable to use a chemical reduction method using a reducing agent suitable for mass production, borohydride compound such as NaBH _4, alkyl borane or Ν _₂ Η ₄ · Η ₂ 0 such as dimethyl Chiruaminboran, N ₂ H ₆ Reduction in the liquid phase using a reducing solution consisting of a reducing agent such as hydrazine hydrate or hydrazine compound such as Cl2 and a solvent such as water or alcohol, or reduction in the gas phase using hydrogen gas, Alternatively, reduction in the gas phase using an inert gas containing hydrazine can be used. Particularly, when manufacturing an electrode for a fuel cell, hydrogen gas or water is used. Preference is given to a method of reducing with an oxygen-containing gas or a method of reducing with an inert gas containing hydrazine.In the case of producing an electrode for a water electrolysis tank, K ₂ PtCl ₆ or K ₂ IrCl ₆ is used as a catalyst raw material compound. In order to prevent the catalyst raw material compound from being eluted from the mixture, a method of reducing the catalyst raw material compound using a reducing solution containing a boron compound using an alcohol having extremely low solubility of the catalyst raw material compound is preferable. Hereinafter, the present invention will be described in further detail by describing a method for producing an electrode for a solid polymer electrolyte fuel cell including a catalyst material composed of two or more metal elements and a solid polymer electrolyte.

Solid polymer electrolyte fuel cells (PEFCs) operate at relatively low temperatures and have high energy-efficiency, so they are expected to be used, for example, as power sources for electric vehicles. Oxidant such as oxygen is supplied to fuel and cathode to generate electricity by electrochemical reaction.

Among them, those that directly supply PEFC methanol to PEFC and directly electrochemically oxidize the methanol in PEFC use direct methanol fuel cell (DMFC). In this DMFC, platinum catalysts commonly used in PEFCs usually have low activity for electrochemical oxidation of methanol, so alloy catalysts containing platinum group metals, such as Pt-Ru alloy Particles of Pt and Sn alloys are used as catalyst materials.

In addition, when hydrogen is used as fuel, methanol is used as the primary fuel, and a reformer utilizing the chemical reaction between methanol and water is used to supply hydrogen, which is obtained by reforming methanol as needed. The fuel cell used in such a method is called a fuel cell reformed fuel cell. Hydrogen sent to a methanol reformed fuel cell often contains about 10 Oppm of CO, so in this fuel cell, the platinum catalyst commonly used for PEFC is greatly affected by CO poisoning. Since no output can be obtained, an alloy catalyst containing a platinum group metal with high resistance to CO poisoning, for example, particles of a Pt—: Ru alloy is used as the catalyst material.

As described above, in PEFC, depending on the fuel or the like used, it is preferable to use a catalyst substance composed of two or more elements such as an alloy.In this case, the catalyst particles and the solid polymer electrolyte described above are combined. In addition to the safety issues during kneading, It is more difficult to uniformly disperse small catalyst particles in a solid polymer electrolyte-catalyst composite electrode than when using a catalyst element composed of a single element.

In such a case, the production method of the present invention particularly exhibits its usefulness, and when a catalyst substance comprising two or more elements such as an alloy catalyst is used, simple and safe, and small catalyst particles are uniformly dispersed. It enables the production of a solid polymer electrolyte-catalyst composite electrode. That is, when producing a solid polymer electrolyte-catalyst composite electrode composed of a catalyst material composed of two or more elements and a solid polymer electrolyte, a mixture of two or more catalyst raw material compounds and a solid polymer electrolyte is used. Prepare and chemically reduce these two or more catalyst raw material compounds.

Then, by using such a method, for example, the catalyst particles include alloy catalyst particles composed of two or more elements and a solid polymer electrolyte, and the catalyst particles are three-dimensionally distributed in the solid polymer electrolyte and internally. A porous electrode with multiple pores, an electron conduction channel formed by highly active catalyst particles, a proton conduction channel formed by a solid electrolyte, and an active material formed by a large number of pores Then, a solid polymer electrolyte-catalyst composite electrode having supply and discharge channels for the product is manufactured. Note that the catalyst substance composed of two or more metal elements refers to alloy particles or mixture particles of a solid solution or an intermetallic compound composed of two or more metal elements.

The two or more catalyst raw material compounds used in this case are compounds that can be converted into a catalyst substance composed of two or more metal elements by reducing these compounds.

As the catalytic substance, a substance having high oxygen reducing ability, hydrogen or CO or methanol oxidizing ability is selected, and such catalytic substances include platinum (Pt), rhodium.

Alloys of platinum group metals such as (Ru), ruthenium (Ru), iridium (Ir), palladium (Pd), and osmium are suitable.

As the catalyst raw material compound, it is preferable to use a platinum group metal compound such as platinum, rhodium, ruthenium, iridium, palladium, and osmium, and among these, a compound having a metal salt form as a compound is preferable. Preferred are, for example, chlorides of platinum group metals.

In addition, electrodes with improved CO poisoning resistance, such as electrodes for methanol reformed fuel cells, etc. When preparing an electrode, when preparing an electrode with improved electrochemical oxidation reaction performance of methanol, such as an electrode for DMFC, at least one of the two or more catalyst raw material compounds must be a platinum group element. It is preferable to include More preferably, at least one of the two or more catalyst raw material compounds contains an element selected from the group consisting of Pt, Ru, Rh, Pd, and Ir. In these cases, in particular, it is preferable that at least two compounds of the catalyst raw material contain at least a compound of platinum and ruthenium, or that two or more catalyst raw materials are used. It is preferable that the compound contains at least a compound of iridium and a compound of ruthenium.

The mixture of two or more catalyst raw material compounds and the solid polymer electrolyte has a liquid / solid state when the two or more catalyst raw material compounds and the solid polymer electrolyte are mixed. However, for example, it is preferable to use a polymorph in which two or more catalyst raw material compounds are uniformly dispersed in a matrix composed of a solid polymer electrolyte having a membrane shape or the like. It is the same as that.

A mixture in which a catalyst raw material compound is dispersed in a matrix composed of a solid polymer electrolyte is made up of a paste comprising two or more catalyst raw material compounds, a solid polymer electrolyte solution, and, if necessary, a PTFE particle dispersion solution. It is formed on a film (preferably ~ 30〃m) and dried by heating.

Alternatively, a paste comprising two or more catalyst raw material compounds and a PTFE particle dispersion solution is formed on a polymer film (preferably, J3Iff 3 to 30 m), dried by heating, and then the solid polymer electrolyte solution is dried. After applying, impregnating and drying,

Alternatively, a paste consisting of two or more catalyst raw material compounds, a solid polymer electrolyte solution, and, if necessary, a PTFE particle dispersion solution is applied to a conductive porous carbon substrate and heated. Dry,

Alternatively, a paste consisting of two or more catalyst raw material compounds and a PTFE particle dispersion solution is applied to a conductive porous carbon electrode, heated and dried, and then a solid polymer electrolyte solution is applied and impregnated. After that, it is preferable to produce it by drying.

In addition, carbon particles may be added to each of the above-described pastes, if necessary. In such a case, carbon particles serve to form the above-described electron conduction channel. Furthermore, a form in which a mixture of two or more catalyst raw material compounds and a solid polymer electrolyte is bonded to both sides or one side of the ion exchange membrane may be used.

To reduce the catalyst raw material compound in the mixture of two or more prepared catalyst raw material compounds and the solid polymer electrolyte, from the viewpoint of safety described above, the catalyst raw material compound and the solid It is preferable to carry out the reaction after sufficiently evaporating the solvent of the solid polymer electrolyte such as alcohol in the mixture with the polymer electrolyte. It is preferable to use a chemical reduction method using a reducing agent suitable for mass production, such as a borohydride such as NaBH ₄ , an alkylamine borane such as dimethylamine borane, or N ₂ H ₄ ′ H _20. , N ₂ reducing agent such as H ₆ C1 ₂ hydrazine hydrate or hydrazine compounds such as water or alcohol - reduction with liquid phase with a reducing solution comprising a solvent such as Le, or hydrogen gas or hydrogen Reduction in the gas phase using a gas containing gas or reduction in the gas phase using an inert gas containing hydrazine can be used.However, in particular, a method of reducing with hydrogen gas or a hydrogen-containing gas Alternatively, a reduction method in a gas phase in which reduction is performed with an inert gas containing hydrazine is preferable because the obtained catalyst substance has higher dispersion and fine particles than a catalyst substance obtained by a reduction method in a liquid phase.

Here, in order to make the catalyst substance obtained by reduction into an alloy composed of two or more metal elements, reduction conditions such as reduction temperature and pressure are selected so that two or more catalyst raw material compounds are reduced simultaneously. Is preferred. Also, in order to make the catalyst substance obtained by reduction a mixture composed of two or more metal elements, the reduction temperature and pressure should be changed over time so that two or more catalyst raw material compounds are sequentially reduced. Is preferred. As described above, it is possible to produce a solid polymer electrolyte-catalyst composite electrode composed of a catalyst material composed of two or more elements and a solid polymer electrolyte. Is particularly excellent as an anode of a fuel cell reformed fuel cell or a direct fuel cell, and the electrode manufactured by the above-described method was used as the anode. A reformed fuel cell or a direct fuel cell can be a very efficient fuel cell. Hereinafter, the present invention will be further described with reference to Examples.

[Example 1]

K ₂ PtCl ₆ (chloroplatinic acid power rim), solid polymer electrolyte solution (Aldrich Co., Nafion 5 wt./. Solution) and PTFE particles (Mitsui DuPont Fluorochemical Co., Ltd., Teflon 30 J, average particle size 0.23 ^ (01) was applied on a conductive porous electrode substrate (0.5 mm) of water-repellent conductive porous material, and dried at 120 ° C for 1 hour in a nitrogen atmosphere.

Subsequently, the dispersion of K ₂ PtCl ₆ and the solid polymer electrolyte was reduced in a hydrogen atmosphere at 50 ° C. and 1 atm for 4 hours to obtain Example electrode A. According to a separate analysis, the platinum amount of the electrode A was about 4 mg / cm ² .

[Comparative Example 1]

Platinum black (N-I-Chemcat, average particle size 1.5 μ-m) pre-moistened with water, solid polymer electrolyte solution (Aldrich, Naphion 5 wt% solution) and PTFE particles (Mitsui DuPont Fluoro) A paste mixed with Teflon 30 J) (Chemical Co., Ltd.) is applied to a conductive porous material (0.5 mm) made of a water-repellent conductive porous material, and then heated to 120 ° C in a nitrogen atmosphere. C and dried for 1 hour to obtain Comparative Example Electrode B.

Here, at the time of preparing the paste, the amount of platinum black was adjusted so that the amount of platinum of the comparative example electrode B was about 4 mg / cm ² .

Example electrode A and comparative example electrode B were bonded to both surfaces of an ion exchange membrane (made by DuPont, trade name: Naphion, film thickness: about 50 m) by hot pressing (140 ° C), respectively. Fig. 1 shows the current-voltage characteristics when cells A and B are assembled into a single fuel cell and hydrogen and oxygen (2 atm, 80 ° C) are supplied to these cells. From the figure, it can be seen that the cell A according to the present invention shows a higher output voltage than the conventional cell B, although it is easily manufactured.

This is because the electrode of the present invention is made by reducing a mixture of a solid polymer electrolyte and a catalyst raw material compound that is reduced to generate a catalyst substance, and thus the catalyst obtained by reduction of the solid polymer electrolyte is used. This is because they exhibit a protective effect by adsorbing on the particles, prevent the catalyst particles from directly contacting each other, and prevent the particles from aggregating, thereby maintaining high activity. As a result of microscopic observation, it was observed that Pt black was agglomerated into particles of 10 to 20 / m in Comparative Example Electrode B, whereas aggregated catalyst particles were observed in Example Electrode A. Absent.

[Example 2]

Mix K ₂ IrCl ₆ (potassium iridium dichloride), K ₂ PtCl ₆ and solid polymer electrolyte solution (Aldrich, Naphion 5 wt% solution) at a weight ratio of 2.0 / 1.0 / 2.77, and mix at 70 ° C After heating and concentrating to obtain a paste having an appropriate viscosity, a film was formed on a FEP (tetrafluoroethylene-hexafluoropropylene copolymer) film and air-dried for 24 hours.

Furthermore, the Irijiumu and mixtures of salt and polymer solid electrolyte platinum respect, the implementation of 70 ° C E evening Roh Ichiru solution for water electrolyzer perform reduction treatment of 2 hours in containing NaBH ₄ in 0.4 wt% Example electrode C was obtained. Analysis was performed separately, it was confirmed that the amount of supported Irijiu arm and platinum electrode C is about 2 mg / cm ² and lmg / cm ^2, respectively.

[Comparative Example 2]

Iridium powder (Tanaka precious metal, average particle diameter 10 zm) pre-moistened with water, platinum black (Nichi-Chemcat, average particle diameter 1.5 キャ m) and solid polymer electrolyte solution 0.8 / 0.4 / Mix at a weight ratio of 2.77, heat and concentrate at 70 ° C to obtain a paste with an appropriate viscosity, and then form a film on FEP (tetrafluoroethylene-hexylene hexafluoropropylene copolymer) film for 24 hours. Was dried naturally to obtain Comparative Example Electrode D.

Here, when making the previous paste was adjusted Irijiumu powder and platinum black amount as the amount of iridium and platinum is about 2 mg / cm ² and lmg / cm ² each of the comparative example electrodes D.

Electrode C of Example and Electrode D of Comparative Example were bonded to both sides of an ion exchange membrane (DuPont, Nafion, Mi-approximately 50 m) by hot pressing (140 ° C) and assembled into a single cell of hydroelectric power. C and D were obtained.

Figure 2 shows the current-voltage characteristics of these cells at 80 ° C. From the figure, it can be seen that the cell according to the present invention has a lower electrolysis voltage than the conventional cell.

This is because the electrode of the present invention is made by reducing a mixture of a solid polymer electrolyte and a compound of a metal exhibiting catalytic activity, so that the solid polymer electrolyte is adsorbed on the catalyst particles obtained by the reduction. Shows a protective effect, and the catalyst particles come into direct contact with each other This is because they prevent aggregation and maintain high activity.

In addition, as a result of microscopic observation, it was observed that the catalyst particles were agglomerated into particles of 30 to 50 m in Comparative Example Electrode D, but no agglomerated catalyst particles were observed in Example Electrode C.

[Example 3]

Water-repellent conductive porous paste made of a mixture of potassium chloroplatinate (K ₂ PtCl ₆ ), ruthenium chloride (RuCl ₃ ), and a solid polymer electrolyte solution (Aldrich, Naphion 5 wt% solution) It was applied on a porous carbon substrate (0.5 mm) and dried at 120 ° C for 1 hour in a nitrogen atmosphere.

Subsequently, a mixture of the above K ₂ Pt Cl ₆ , ruthenium chloride (RuCl ₃ ) and a solid polymer electrolyte solution was reduced in a hydrogen atmosphere at 200 ° C. and 1 atm for 4 hours to obtain Example electrode E. According to the analysis performed separately, the amount of platinum and the amount of ruthenium of the electrode E were about 3 mg / cm ² respectively.

[Comparative Example 3]

A conductive porous material with water repellency, obtained by mixing a paste in which Pt_Ru0X fine powder pre-wetted with water and a solid polymer electrolyte solution (Aldrich Co., Ltd., Naphion 5 wt% solution) are mixed. Was applied on a carbon electrode substrate (0.5 mm) of Example 1 and dried at 120 ° C. for 1 hour in a nitrogen atmosphere to obtain Comparative Example Electrode F. Here, when preparing the paste, the amount of platinum black was adjusted so that the amount of platinum and the amount of ruthenium of the comparative electrode F were about 3 mg / cm ² respectively.

The electrode E of Example and the electrode F of Comparative Example were hot-pressed (140 ° C) on both sides of an ion-exchange membrane (made by DuPont, trade name: Naphion, film thickness: approx. The cells were joined and assembled into a single cell of a fuel cell to obtain cells E and F.

Figure 3 shows the current-voltage characteristics when hydrogen containing 10 Oppm of CO was supplied as fuel to these cells and oxygen (2 atm, 80 ° C) was supplied as oxidant. From the figure, it can be seen that the cell E according to the present invention has good resistance to CO poisoning and shows a higher output voltage than the conventional cell F, although it is easily manufactured.

This is because the electrode of the present invention is a catalyst raw material compound which is reduced to produce a catalyst substance and a solid. The solid polymer electrolyte is adsorbed on the catalyst particles obtained by the reduction, and the catalyst particles come into direct contact with each other to aggregate the particles. This is because the catalyst particles maintain high activity.

According to the production method of the present invention, a solid polymer composed of a solid polymer electrolyte and a catalyst substance is safely and easily exhibited by a simple device without hindering the catalytic activity of the catalyst substance. An electrolyte-catalyst composite electrode can be manufactured.

Further, the electrode comprising a catalyst material comprising two or more metal elements and a solid polymer electrolyte produced by the present invention is a modified methanol fuel cell or DMFC which requires an alloy catalyst for the oxidation reaction of fuel at the electrode. Is particularly preferable as the anode electrode.

Claims

The scope of the claims

1. A method for producing a solid polymer electrolyte-catalyst composite electrode comprising a solid polymer electrolyte and a catalyst substance, wherein a mixture of a catalyst raw material compound that is reduced to generate a catalyst substance and a solid polymer electrolyte is used. A method for producing a solid polymer electrolyte-catalyst composite electrode, comprising preparing and chemically reducing a catalyst raw material compound in the mixture.

2. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 1, wherein the catalyst raw material compound is a compound of a platinum group metal.

3. The solid polymer electrolyte-catalyst composite electrode according to claim 1, wherein the catalyst substance is composed of two or more metal elements, and two or more catalyst raw material compounds are used as the catalyst raw material compound. Production method.

4. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 3, wherein at least one of the two or more catalyst raw material compounds is a platinum group metal compound. 5. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 4, wherein the two or more catalyst raw material conjugates contain at least a platinum compound and a ruthenium compound.

6. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 4, wherein the two or more catalyst raw material compounds include at least an iridium compound and a ruthenium compound.

7. The method for producing a solid polymer electrolyte-catalyst composite electrode according to any one of claims 1, 2, 3, 4, 5, and 6, wherein the catalyst raw material is reduced with hydrogen gas or hydrogen-containing gas. Method.

8. The method for producing a solid polymer electrolyte-catalyst composite electrode according to any one of claims 1, 2, 3, 4, 5, and 6, wherein the catalyst raw material compound is reduced with an inert gas containing hydrazine.

9. Using K ₂ PtCl ₆ or / and K ₂ IrCl ₆ as a catalyst raw material conjugate, reducing the catalyst raw material compound using a reducing solution containing a boron compound using alcohols as a solvent. 3. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 1 or 2.

10. A methanol-modified fuel cell or direct methanol, wherein a solid polymer electrolyte-catalyst composite electrode produced by the production method according to claim 3, 4, 5, or 6 is used as an anode. Type fuel cell.

Claims on the certificate

[199.1 January 1st January 16th (16.1.1.99) Accepted by the International Bureau: Claims originally filed 1–10 are renumbered to claims 1–1 4 Was. (2 pages)] Claims

1. A method for producing a solid polymer electrolyte-catalyst composite electrode comprising a solid polymer electrolyte and a catalyst substance, wherein a mixture of a catalyst raw material compound which is reduced to produce a catalyst substance and a solid polymer electrolyte is used. A method for producing a solid polymer electrolyte-catalyst composite electrode, comprising preparing and chemically reducing a catalyst raw material compound in the mixture.

2. (Addition) A method for producing a solid polymer electrolyte-catalyst composite electrode, wherein the mixture according to claim 1 is a solid.

3. (Addition) A method for producing a solid polymer electrolyte-catalyst composite electrode, wherein the mixture according to claim 1 is a porous solid.

4. (Addition) A solid polymer electrolyte-catalyst composite m @ il method, wherein the mixture according to claim 1, 2 or 3 contains carbon particles or PTFE particles.

5. (Addition) A solid polymer electrolyte monocatalyst characterized in that the mixture according to Claims 1, 2, 3 or 4 is coated on a molecular film or carbon of a conductive porous material by Ml coating or coating. A method for manufacturing a composite electrode.

6. (After correction) The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 1, 2, 3, 4 or 5, wherein the catalyst raw material compound is a compound of a platinum group metal.

7. The method according to claim 1, 2, or 3, wherein the (after amendment) catalyst substance is composed of two or more metal elements, and two or more catalyst raw material compounds are used as the catalyst raw material. 6. The method for producing a solid polymer electrolyte-catalyst composite electrode according to item 4, 4 or 5.

8. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 7, wherein at least one of the two or more catalyst raw material compounds is a platinum group metal compound.

9. (after correction) The production of a solid polymer electrolyte-catalyst composite electrode according to claim 8, wherein the two or more catalyst raw material compounds contain at least a platinum compound and a ruthenium compound. Method.

10. The solid height according to claim 8, wherein (after correction) the two or more catalyst raw material compounds contain at least an iridium compound and a ruthenium compound.

1 6 Captured paper (Article 19 of the Convention) A method for producing a molecular electrolyte-catalyst composite electrode.

(After amendment) Claims 1, 2, 3, 4, 5, 6, 7, 8, 9 or 9 characterized in that the catalyst raw material is reduced by hydrogen gas or hydrogen-containing gas. 10. The method for producing a solid polymer electrolyte-catalyst composite electrode according to 10 above.

12. (After Correction) Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 characterized in that the catalyst raw material compound is reduced by an inert gas containing hydrazine. Method for producing a solid polymer electrolyte-catalyst composite electrode.

1 3. With K ₂ PtCl6 or / and Κ ₂ Μ¾ as (corrected) catalyst starting compound, that the catalyst material I匕合thereof to reduction have use a reducing solution containing a boron compound was an alcohol as a solvent 7. The method for producing a solid polymer electrolyte-catalyst composite electrode according to claim 1, 2, 3, 4, 5, or 6.

14. (After amendment) A solid polymer electrolyte-catalyst composite m¾ produced by the production method according to claims 7, 8, 9 or 10 is used as an anode. Either a reformed fuel cell or a direct methanol fuel cell.

1 7 Amended paper (Article 19 of the Convention)